Below are possible answers for the crossword clue Sort of rule you can't look up?.
9 letter answer(s) to sort of rule you can't look up?
UNWRITTEN
based on custom rather than documentation; "an unwritten law"; "rites...so ancient that they well might have had their unwritten origins in Aurignacian times"- J.L.T.C.Spence
said or done without having been planned or written in advance; "he made a few ad-lib remarks"
using speech rather than writing; "an oral tradition"; "an oral agreement"
Other crossword clues with similar answers to 'Sort of rule you can't look up?'